Adding error handling for function argument errors.

LogarithmPlotter/i18n/lp_de.ts

@@ -1046,6 +1046,14 @@ Evaluated expression: %3</source>
 
 Ausdruck analysiert: %3</translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="179"/>
+        <source>Error while attempting to draw %1 %2:
+%3
+
+Undoing last change.</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>expression</name>
@@ -1066,6 +1074,11 @@ Evaluated expression: %3</source>
 
 Ausdruck analysiert: %3</translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="176"/>
+        <source>LogarithmPlotter - Drawing error</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>function</name>

LogarithmPlotter/i18n/lp_en.ts

@@ -1046,6 +1046,14 @@ Evaluated expression: %3</source>
 
 Evaluated expression: %3</translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="179"/>
+        <source>Error while attempting to draw %1 %2:
+%3
+
+Undoing last change.</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>expression</name>
@@ -1066,6 +1074,11 @@ Evaluated expression: %3</source>
 
 Evaluated expression: %3</translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="176"/>
+        <source>LogarithmPlotter - Drawing error</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>function</name>

LogarithmPlotter/i18n/lp_es.ts

@@ -991,6 +991,14 @@ These settings can be changed at any time from the &quot;Settings&quot; menu.</s
 Evaluated expression: %3</source>
         <translation type="unfinished"></translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="179"/>
+        <source>Error while attempting to draw %1 %2:
+%3
+
+Undoing last change.</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>expression</name>
@@ -1008,6 +1016,11 @@ Evaluated expression: %3</source>
 Evaluated expression: %3</source>
         <translation type="unfinished"></translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="176"/>
+        <source>LogarithmPlotter - Drawing error</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>function</name>

LogarithmPlotter/i18n/lp_fr.ts

@@ -1055,6 +1055,14 @@ Evaluated expression: %3</source>
 
 Formule analysée : %3</translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="179"/>
+        <source>Error while attempting to draw %1 %2:
+%3
+
+Undoing last change.</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>expression</name>
@@ -1075,6 +1083,11 @@ Evaluated expression: %3</source>
 
 Formule analysée : %3</translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="176"/>
+        <source>LogarithmPlotter - Drawing error</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>function</name>

LogarithmPlotter/i18n/lp_hu.ts

@@ -1046,6 +1046,14 @@ Evaluated expression: %3</source>
 
 Kiértékelt kifejezés: %3</translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="179"/>
+        <source>Error while attempting to draw %1 %2:
+%3
+
+Undoing last change.</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>expression</name>
@@ -1066,6 +1074,11 @@ Evaluated expression: %3</source>
 
 Kiértékelt kifejezés: %3</translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="176"/>
+        <source>LogarithmPlotter - Drawing error</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>function</name>

LogarithmPlotter/i18n/lp_nb_NO.ts

@@ -1043,6 +1043,14 @@ Disse innstillingene kan endres når som helst fra «Innstillinger»-menyen.</tr
 Evaluated expression: %3</source>
         <translation type="unfinished"></translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="179"/>
+        <source>Error while attempting to draw %1 %2:
+%3
+
+Undoing last change.</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>expression</name>
@@ -1060,6 +1068,11 @@ Evaluated expression: %3</source>
 Evaluated expression: %3</source>
         <translation type="unfinished"></translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="176"/>
+        <source>LogarithmPlotter - Drawing error</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>function</name>

LogarithmPlotter/i18n/lp_template.ts

@@ -991,6 +991,14 @@ These settings can be changed at any time from the &quot;Settings&quot; menu.</s
 Evaluated expression: %3</source>
         <translation type="unfinished"></translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="179"/>
+        <source>Error while attempting to draw %1 %2:
+%3
+
+Undoing last change.</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>expression</name>
@@ -1008,6 +1016,11 @@ Evaluated expression: %3</source>
 Evaluated expression: %3</source>
         <translation type="unfinished"></translation>
     </message>
+    <message>
+        <location filename="../qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml" line="176"/>
+        <source>LogarithmPlotter - Drawing error</source>
+        <translation type="unfinished"></translation>
+    </message>
 </context>
 <context>
     <name>function</name>

LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/LogGraphCanvas.qml

@@ -17,6 +17,7 @@
  */
 
 import QtQuick
+import Qt.labs.platform as Native
 import "js/objects.js" as Objects
 import "js/utils.js" as Utils
 import "js/mathlib.js" as MathLib
@@ -170,6 +171,16 @@ Canvas {
     
     Component.onCompleted: imageLoaders = {}
     
+    Native.MessageDialog {
+        id: drawingErrorDialog
+        title: qsTranslate("expression", "LogarithmPlotter - Drawing error")
+        text: ""
+        function showDialog(objType, objName, error) {
+            text = qsTranslate("error", "Error while attempting to draw %1 %2:\n%3\n\nUndoing last change.").arg(objType).arg(objName).arg(error)
+            open()
+        }
+    }
+    
     onPaint: function(rect) {
         //console.log('Redrawing')
         if(rect.width == canvas.width) { // Redraw full canvas
@@ -183,7 +194,14 @@ Canvas {
                 for(var obj of Objects.currentObjects[objType]){
                     ctx.strokeStyle = obj.color
                     ctx.fillStyle = obj.color
-                    if(obj.visible) obj.draw(canvas, ctx)
+                    if(obj.visible)
+                        try {
+                            obj.draw(canvas, ctx)
+                        } catch(e) {
+                            // Drawing throws an error. Generally, it's due to a new modification (or the opening of a file)
+                            drawingErrorDialog.showDialog(objType, obj.name, e.message)
+                            history.undo()
+                        }
                 }
             }
             ctx.lineWidth = 1