Ignore errors from builtin functions in non strict mode (#154)

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

src/interpreter.rs

@@ -2055,7 +2055,12 @@ impl Interpreter {
             }
         }
 
-        let v = builtin.0(span, params, &args[..], self.strict_builtin_errors)?;
+        let v = match builtin.0(span, params, &args[..], self.strict_builtin_errors) {
+            Ok(v) => v,
+            // Ignore errors if we are not evaluating in strict mode.
+            Err(_) if !self.strict_builtin_errors => return Ok(Value::Undefined),
+            Err(e) => Err(e)?,
+        };
 
         // Handle trace function.
         // TODO: with modifier.

tests/interpreter/cases/nonstrict/tests.yaml

@@ -0,0 +1,19 @@
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+  cases:
+    - note: builtin error gobbled up in non strict mode
+      modules:
+        - |
+          package test
+          a = to_number("abc")
+      query: data.test
+      want_result: {}
+      strict: false
+
+    - note: builtin error in strict mode
+      modules:
+        - |
+          package test
+          a = to_number("abc")
+      query: data.test
+      error: "could not parse string as number"