lex invalid input gracefully in case it is after 'end' op

lex.go

@@ -176,8 +176,13 @@ func lexInput(l *lexer) lexStateFn {
 	case '\x1a':
 		return l.consume(lexInput)
 	default:
+		// we will put this in the stream. if a file is formatted
+		// properly, and invalid input should be after an 'end'
+		// pseudo-op which will cause the parser to stop before
+		// processing this token, otherwise it is an error
 		l.tokens <- token{tokInvalid, string(l.nextRune)}
-		return l.consume(lexInput)
+		l.tokens <- token{typ: tokEOF}
+		return nil
 	}
 
 	return nil

symbol_scanner.go

@@ -14,7 +14,6 @@ type symbolScanner struct {
 
 	nextToken token
 	atEOF     bool
-	endSeen   bool
 	valBuf    []token
 	labelBuf  []string
 	forLevel  int
@@ -109,7 +108,6 @@ func scanLabels(p *symbolScanner) scanStateFn {
 				}
 				return scanConsumeLine
 			case "end":
-				p.endSeen = true
 				if p.forLevel > 1 {
 					return scanConsumeLine
 				} else {
@@ -120,13 +118,8 @@ func scanLabels(p *symbolScanner) scanStateFn {
 			}
 		} else if p.nextToken.IsOp() {
 			return scanConsumeLine
-		} else if p.nextToken.typ == tokError {
-			if p.endSeen {
-				return nil
-			} else {
-
-				return nil
-			}
+		} else if p.nextToken.typ == tokInvalid {
+			return nil
 		}
 		p.labelBuf = append(p.labelBuf, p.nextToken.val)
 		return p.consume(scanLabels)

symbol_scanner_test.go

@@ -54,6 +54,10 @@ func TestSymbolScanner(t *testing.T) {
 				"test": {{tokNumber, "2"}},
 			},
 		},
+		{
+			input:  "for 1\nend\nrof\n ~",
+			output: map[string][]token{},
+		},
 	}
 	runSymbolScannerTests(t, tests)
 }