Return NonKayveeError if log contians invalid or empty json

decode/decode.go

@@ -83,8 +83,14 @@ func FieldsFromKayvee(line string) (map[string]interface{}, error) {
 	possibleJSON := line[firstIdx : lastIdx+1]
 	var fields map[string]interface{}
 	if err := json.Unmarshal([]byte(possibleJSON), &fields); err != nil {
-		return map[string]interface{}{}, err
+		return map[string]interface{}{}, &NonKayveeError{}
 	}
+
+	if len(fields) == 0 { // Some logs superfluous "{}" in them.  They're not kayvee.
+		return map[string]interface{}{}, &NonKayveeError{}
+	}
+	// TODO: consider also filter if they have source and title
+
 	for k, v := range fields {
 		if !stringInSlice(k, reservedFields) {
 			m[k] = v

decode/decode_test.go

@@ -1,7 +1,6 @@
 package decode
 
 import (
-	"encoding/json"
 	"fmt"
 	"testing"
 	"time"
@@ -75,7 +74,13 @@ func TestKayveeDecoding(t *testing.T) {
 			Title:          "errors on invalid JSON (missing a quote)",
 			Input:          `prefix {"a:"b"} postfix`,
 			ExpectedOutput: map[string]interface{}{},
-			ExpectedError:  &json.SyntaxError{},
+			ExpectedError:  &NonKayveeError{},
+		},
+		Spec{
+			Title:          "errors on empty JSON: {}",
+			Input:          `prefix {} postfix`,
+			ExpectedOutput: map[string]interface{}{},
+			ExpectedError:  &NonKayveeError{},
 		},
 	}