internal/function: recover from panics in uast functions

Signed-off-by: Miguel Molina <miguel@erizocosmi.co>

Author: erizocosmico

internal/function/uast.go

@@ -115,7 +115,13 @@ func (f UAST) String() string {
 }
 
 // Eval implements the Expression interface.
-func (f UAST) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
+func (f UAST) Eval(ctx *sql.Context, row sql.Row) (out interface{}, err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			err = fmt.Errorf("uast: unknown error: %s", r)
+		}
+	}()
+
 	span, ctx := ctx.Span("gitbase.UAST")
 	defer span.Finish()
 
@@ -246,7 +252,13 @@ func (UASTXPath) Type() sql.Type {
 }
 
 // Eval implements the Expression interface.
-func (f *UASTXPath) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
+func (f *UASTXPath) Eval(ctx *sql.Context, row sql.Row) (out interface{}, err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			err = fmt.Errorf("uastxpath: unknown error: %s", r)
+		}
+	}()
+
 	span, ctx := ctx.Span("gitbase.UASTXPath")
 	defer span.Finish()