Update utils.go

Fixes breakage caused by #1434

build/utils.go

diff --git a/build/utils.go b/build/utils.go
index c0b2bd3..bb72508 100644
--- a/build/utils.go
+++ b/build/utils.go
@@ -83,5 +83,9 @@
 // IsMultiLine returns whether an Expr is multiline or not.
 func IsMultiLine(param Expr) bool {
 	start, end := param.Span()
+	if end.Line == 0 && end.Byte == 0 && end.LineRune == 0 {
+		// If the end position is unknown, we assume it's single line (for backwards compatibility).
+		return false
+	}
 	return start.Line != end.Line
 }