From 7671e4ea8b4544110bf41b85d819ac66959efbd8 Mon Sep 17 00:00:00 2001
From: Thorsten Riess <tr@scientific-wave.com>
Date: Fri, 21 May 2021 14:28:27 +0200
Subject: [PATCH] Fix panic if there is a nil in a map[...]interface{} value

---
 convert.go      | 17 +++++++++++++++++
 convert_test.go | 15 +++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/convert.go b/convert.go
index bd6523e..6c0c3b6 100644
--- a/convert.go
+++ b/convert.go
@@ -177,6 +177,9 @@ func (ce *ConverterEngine) Convert(source interface{}, targetType reflect.Type)
 		if ok {
 			return kind2Exact(stringer.String(), targetType), nil
 		}
+		if sourceType == nil {
+			return kind2Exact("", targetType), nil
+		}
 		// Convert to string typical value types
 		switch sourceType.Kind() {
 		case reflect.Bool:
@@ -191,6 +194,20 @@ func (ce *ConverterEngine) Convert(source interface{}, targetType reflect.Type)
 
 	}
 
+	if sourceType == nil {
+		switch targetType.Kind() {
+		case reflect.String:
+			return kind2Exact("", targetType), nil
+		case reflect.Bool:
+			return kind2Exact(false, targetType), nil
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			return kind2Exact(0, targetType), nil
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			return kind2Exact(0, targetType), nil
+		case reflect.Float32, reflect.Float64:
+			return kind2Exact(0.0, targetType), nil
+		}
+	}
 	if sourceType.Kind() == reflect.String {
 		// Attempt to parse typical value types from the string
 		switch targetType.Kind() {
diff --git a/convert_test.go b/convert_test.go
index 82ad32f..9de829e 100644
--- a/convert_test.go
+++ b/convert_test.go
@@ -105,19 +105,34 @@ var testData = []ConversionTest{
 		"uno":  1,
 		"dos":  2,
 		"tres": 3,
+		"nil": nil,
 	}, map[string]int{
 		"uno":  1,
 		"dos":  2,
 		"tres": 3,
+		"nil": 0,
 	}, nil},
 	{map[string]interface{}{
 		"1": "uno",
 		"2": "dos",
 		"3": "tres",
+		"4": nil,
 	}, map[int]string{
 		1: "uno",
 		2: "dos",
 		3: "tres",
+		4: "",
+	}, nil},
+	{map[string]interface{}{
+		"uno":  1,
+		"dos":  2,
+		"tres": 3,
+		"nil": nil,
+	}, map[string]int{
+		"uno":  1,
+		"dos":  2,
+		"tres": 3,
+		"nil": 0,
 	}, nil},
 	{[]byte{65, 66, 67, 0}, "ABC\x00", nil},
 	{"ABC\x00", []byte{65, 66, 67, 0}, nil},