[processor/filter] prevent the matcher from panicking (#14147)

* [processor/filter] prevent the matcher from panicking

Signed-off-by: Benedikt Bongartz <bongartz@klimlive.de>

* [processor/filter] add changelog

Signed-off-by: Benedikt Bongartz <bongartz@klimlive.de>

Signed-off-by: Benedikt Bongartz <bongartz@klimlive.de>

internal/coreinternal/processor/filterexpr/matcher.go

@@ -15,6 +15,8 @@
 package filterexpr // import "github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal/processor/filterexpr"
 
 import (
+	"fmt"
+
 	"github.com/antonmedv/expr"
 	"github.com/antonmedv/expr/vm"
 	"go.opentelemetry.io/collector/pdata/pcommon"
@@ -151,5 +153,12 @@ func (m *Matcher) match(env env) (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	return result.(bool), nil
+
+	v, ok := result.(bool)
+	if !ok {
+		return false, fmt.Errorf("filter returned non-boolean value type=%T result=%v metric=%s, attributes=%v",
+			result, result, env.MetricName, env.attributes.AsRaw())
+	}
+
+	return v, nil
 }

unreleased/processor-filter_prevent_panic.yaml

@@ -0,0 +1,11 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: filterexpr
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: prevent the matcher from panicking
+
+# One or more tracking issues related to the change
+issues: [13573]