Fix error in markdown parsing image dimensions (#6518)

Gracefully handle parsing failures for image width and height in Markdown. Unit tests are provided.

Fixes flutter/flutter#146739

Author: collinjackson

packages/flutter_markdown/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.6.23
+
+* Gracefully handle image dimension parsing failures.
+
 ## 0.6.22+1
 
 * Removes `_ambiguate` methods from code.

packages/flutter_markdown/lib/src/builder.dart

@@ -568,8 +568,8 @@ class MarkdownBuilder implements md.NodeVisitor {
     if (parts.length == 2) {
       final List<String> dimensions = parts.last.split('x');
       if (dimensions.length == 2) {
-        width = double.parse(dimensions[0]);
-        height = double.parse(dimensions[1]);
+        width = double.tryParse(dimensions[0]);
+        height = double.tryParse(dimensions[1]);
       }
     }
 

packages/flutter_markdown/pubspec.yaml

@@ -4,7 +4,7 @@ description: A Markdown renderer for Flutter. Create rich text output,
   formatted with simple Markdown tags.
 repository: https://github.com/flutter/packages/tree/main/packages/flutter_markdown
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+flutter_markdown%22
-version: 0.6.22+1
+version: 0.6.23
 
 environment:
   sdk: ^3.3.0

packages/flutter_markdown/test/image_test.dart

@@ -333,6 +333,42 @@ void defineTests() {
       },
     );
 
+    testWidgets(
+      'should gracefully handle width parsing failures',
+      (WidgetTester tester) async {
+        const String data = '![alt](https://img#x50)';
+        await tester.pumpWidget(
+          boilerplate(
+            const Markdown(data: data),
+          ),
+        );
+
+        final Image image = tester.widget(find.byType(Image));
+        final NetworkImage networkImage = image.image as NetworkImage;
+        expect(networkImage.url, 'https://img');
+        expect(image.width, null);
+        expect(image.height, 50);
+      },
+    );
+
+    testWidgets(
+      'should gracefully handle height parsing failures',
+      (WidgetTester tester) async {
+        const String data = ' ![alt](https://img#50x)';
+        await tester.pumpWidget(
+          boilerplate(
+            const Markdown(data: data),
+          ),
+        );
+
+        final Image image = tester.widget(find.byType(Image));
+        final NetworkImage networkImage = image.image as NetworkImage;
+        expect(networkImage.url, 'https://img');
+        expect(image.width, 50);
+        expect(image.height, null);
+      },
+    );
+
     testWidgets(
       'custom image builder',
       (WidgetTester tester) async {