Improve error message when encountering an invalid tsconfig.json file.

src/compiler/commandLineParser.ts

@@ -299,7 +299,7 @@ module ts {
       * @param basePath A root directory to resolve relative path entries in the config
       *    file to. e.g. outDir 
       */
-    export function parseConfigFile(json: any, host: ParseConfigHost, basePath?: string): ParsedCommandLine {
+    export function parseConfigFile(json: any, host: ParseConfigHost, basePath: string): ParsedCommandLine {
         var errors: Diagnostic[] = [];
 
         return {

src/compiler/diagnosticInformationMap.generated.ts

@@ -439,6 +439,7 @@ module ts {
         Cannot_find_the_common_subdirectory_path_for_the_input_files: { code: 5009, category: DiagnosticCategory.Error, key: "Cannot find the common subdirectory path for the input files." },
         Cannot_read_file_0_Colon_1: { code: 5012, category: DiagnosticCategory.Error, key: "Cannot read file '{0}': {1}" },
         Unsupported_file_encoding: { code: 5013, category: DiagnosticCategory.Error, key: "Unsupported file encoding." },
+        Failed_to_parse_file_0_Colon_1: { code: 5014, category: DiagnosticCategory.Error, key: "Failed to parse file '{0}': {1}." },
         Unknown_compiler_option_0: { code: 5023, category: DiagnosticCategory.Error, key: "Unknown compiler option '{0}'." },
         Compiler_option_0_requires_a_value_of_type_1: { code: 5024, category: DiagnosticCategory.Error, key: "Compiler option '{0}' requires a value of type {1}." },
         Could_not_write_file_0_Colon_1: { code: 5033, category: DiagnosticCategory.Error, key: "Could not write file '{0}': {1}" },

src/compiler/diagnosticMessages.json

@@ -1744,6 +1744,10 @@
         "category": "Error",
         "code": 5013
     },
+    "Failed to parse file '{0}': {1}.": {
+        "category": "Error",
+        "code": 5014
+    },
     "Unknown compiler option '{0}'.": {
         "category": "Error",
         "code": 5023

src/compiler/tsc.ts

@@ -208,9 +208,12 @@ module ts {
 
             if (!cachedProgram) {
                 if (configFileName) {
-                    var configObject = readConfigFile(configFileName);
-                    if (!configObject) {
-                        reportDiagnostic(createCompilerDiagnostic(Diagnostics.Unable_to_open_file_0, configFileName));
+                    try {
+                        var configObject = readConfigFile(configFileName);
+                    }
+                    catch (e)
+                    {
+                        reportDiagnostic(createCompilerDiagnostic(Diagnostics.Failed_to_parse_file_0_Colon_1, configFileName, e.message));
                         return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
                     }
                     var configParseResult = parseConfigFile(configObject, sys, getDirectoryPath(configFileName));

src/services/shims.ts

@@ -811,7 +811,7 @@ module ts {
                         return {
                             options: {},
                             files: [],
-                            errors: realizeDiagnostic(createCompilerDiagnostic(Diagnostics.Unable_to_open_file_0, fileName), '\r\n')
+                            errors: realizeDiagnostic(createCompilerDiagnostic(Diagnostics.Failed_to_parse_file_0_Colon_1, fileName, e.message), '\r\n')
                         }
                     }