Move milliseconds factor to a constant

This makes it less likely to run into weird bugs if we need to tweak
the value in the future.

lib/helpers/charts.dart

@@ -1,5 +1,9 @@
+import 'consts.dart';
+
 double chartGetInterval(DateTime first, DateTime last, {divider = 3}) {
   final dayDiff = last.difference(first);
 
-  return dayDiff.inMilliseconds == 0 ? 1000000 : dayDiff.inMilliseconds.abs() / divider;
+  return dayDiff.inMilliseconds == 0
+      ? CHART_MILLISECOND_FACTOR
+      : dayDiff.inMilliseconds.abs() / divider;
 }

lib/helpers/consts.dart

@@ -112,3 +112,9 @@ const COLOR_SECONDARY_MUSCLES = Colors.orange;
 // Min account age to contribute exercises. Needs to be kept in sync with
 // the value on the backend
 const MIN_ACCOUNT_AGE = 14;
+
+/// Factor to multiply / divide in the charts when converting dates to milliseconds
+/// from epoch since fl_charts does not support real time series charts and using
+/// the milliseconds themselves can cause the application to crash since it runs
+/// out of memory...
+const double CHART_MILLISECOND_FACTOR = 100000.0;

lib/widgets/measurements/charts.dart

@@ -20,6 +20,7 @@ import 'package:fl_chart/fl_chart.dart';
 import 'package:flutter/material.dart';
 import 'package:intl/intl.dart';
 import 'package:wger/helpers/charts.dart';
+import 'package:wger/helpers/consts.dart';
 import 'package:wger/l10n/generated/app_localizations.dart';
 
 class MeasurementOverallChangeWidget extends StatelessWidget {
@@ -142,7 +143,7 @@ class _MeasurementChartWidgetFlState extends State<MeasurementChartWidgetFl> {
                     widget._entries.last.date,
                     widget._entries.first.date,
                   )
-                : 1000000,
+                : CHART_MILLISECOND_FACTOR,
           ),
         ),
         leftTitles: AxisTitles(

lib/widgets/measurements/helpers.dart

@@ -78,13 +78,15 @@ List<Widget> getOverviewWidgetsSeries(
       mainAxisAlignment: MainAxisAlignment.center,
       children: [
         Indicator(
-            color: Theme.of(context).colorScheme.primary,
-            text: AppLocalizations.of(context).indicatorRaw,
-            isSquare: true),
+          color: Theme.of(context).colorScheme.primary,
+          text: AppLocalizations.of(context).indicatorRaw,
+          isSquare: true,
+        ),
         Indicator(
-            color: Theme.of(context).colorScheme.tertiary,
-            text: AppLocalizations.of(context).indicatorAvg,
-            isSquare: true),
+          color: Theme.of(context).colorScheme.tertiary,
+          text: AppLocalizations.of(context).indicatorAvg,
+          isSquare: true,
+        ),
       ],
     ),
   ];