Fixes #5139: Improve YAML error line number extraction for .roomodes files

- Enhanced line number extraction in CustomModesManager to handle multiple YAML error message formats
- Added support for patterns: 'at line X', 'line X', '(line:column)', and 'line:column'
- Ensures robust error reporting when .roomodes files have YAML syntax errors
- Maintains backward compatibility with existing error handling

src/core/config/CustomModesManager.ts

@@ -134,8 +134,23 @@ export class CustomModesManager {
 					const errorMsg = yamlError instanceof Error ? yamlError.message : String(yamlError)
 					console.error(`[CustomModesManager] Failed to parse YAML from ${filePath}:`, errorMsg)
 
-					const lineMatch = errorMsg.match(/at line (\d+)/)
-					const line = lineMatch ? lineMatch[1] : "unknown"
+					// Try multiple patterns to extract line number from YAML error messages
+					const linePatterns = [
+						/at line (\d+)/, // "at line X"
+						/line (\d+)/, // "line X"
+						/\((\d+):\d+\)/, // "(line:column)"
+						/(\d+):\d+/, // "line:column"
+					]
+
+					let line = "unknown"
+					for (const pattern of linePatterns) {
+						const match = errorMsg.match(pattern)
+						if (match) {
+							line = match[1]
+							break
+						}
+					}
+
 					vscode.window.showErrorMessage(t("common:customModes.errors.yamlParseError", { line }))
 
 					// Return empty object to prevent duplicate error handling