parse: remove unneeded state transitions

this was found after adding more test cases
and finding that those lines were not covered

Author: neiser

parse/lex.go

@@ -246,10 +246,6 @@ func lexSubstitution(l *lexer) stateFn {
 		l.subsDepth--
 		l.emit(itemRightDelim)
 		return lexText
-	case r == eof || isEndOfLine(r):
-		return l.errorf("closing brace expected")
-	case isAlphaNumeric(r) && strings.HasPrefix(l.input[l.lastPos:], "${"):
-		fallthrough
 	case r == '$':
 		return lexVariable
 	default: