Fix tests for PR antlr#1844.

Author: davesisson

doc/go-target.md

@@ -88,7 +88,7 @@ func (this *TreeShapeListener) EnterEveryRule(ctx antlr.ParserRuleContext) {
 }
 
 func main() {
-	input := antlr.NewFileStream(os.Args[1])
+	input, _ := antlr.NewFileStream(os.Args[1])
 	lexer := parser.NewJSONLexer(input)
 	stream := antlr.NewCommonTokenStream(lexer,0)
 	p := parser.NewJSONParser(stream)

runtime-testsuite/test/org/antlr/v4/test/runtime/go/BaseGoTest.java

@@ -696,7 +696,11 @@ protected void writeParserTestFile(String parserName, String lexerName,
 				+ "}\n"
 				+ "\n"
 				+ "func main() {\n"
-				+ "	input := antlr.NewFileStream(os.Args[1])\n"
+				+ "	input, err := antlr.NewFileStream(os.Args[1])\n"
+				+ "     if err != nil {\n"
+				+ "     	fmt.Printf("Failed to find file: %v", err)\n"
+				+ "     	return\n"
+				+ "     }\n"
 				+ "	lexer := parser.New<lexerName>(input)\n"
 				+ "	stream := antlr.NewCommonTokenStream(lexer,0)\n"
 				+ "<createParser>"