[DevTools] Avoid assertion failure

third_party/WebKit/Source/devtools/front_end/sources/SourcesPanel.js

Index: third_party/WebKit/Source/devtools/front_end/sources/SourcesPanel.js
diff --git a/third_party/WebKit/Source/devtools/front_end/sources/SourcesPanel.js b/third_party/WebKit/Source/devtools/front_end/sources/SourcesPanel.js
index 97e65501799ff1df114640446743a50f726c7ed9..9bd0b4e021b8edd6eb5d70d3eda5befffd00d35d 100644
--- a/third_party/WebKit/Source/devtools/front_end/sources/SourcesPanel.js
+++ b/third_party/WebKit/Source/devtools/front_end/sources/SourcesPanel.js
@@ -538,6 +538,9 @@ Sources.SourcesPanel = class extends UI.Panel {
     if (!currentExecutionContext)
       return false;
 
+    if (uiSourceCode.project().type() !== Workspace.projectTypes.Snippets)
+      return false;
+
     Snippets.scriptSnippetModel.evaluateScriptSnippet(currentExecutionContext, uiSourceCode);
     return true;
   }