fix: do not allow setting dependencies to nil values

Signed-off-by: Mark Sagi-Kazar <mark.sagikazar@gmail.com>

encoding.go

@@ -58,6 +58,10 @@ type CodecRegistry interface {
 // WithEncoderRegistry sets a custom [EncoderRegistry].
 func WithEncoderRegistry(r EncoderRegistry) Option {
 	return optionFunc(func(v *Viper) {
+		if r == nil {
+			return
+		}
+
 		v.encoderRegistry = r
 	})
 }
@@ -65,6 +69,10 @@ func WithEncoderRegistry(r EncoderRegistry) Option {
 // WithDecoderRegistry sets a custom [DecoderRegistry].
 func WithDecoderRegistry(r DecoderRegistry) Option {
 	return optionFunc(func(v *Viper) {
+		if r == nil {
+			return
+		}
+
 		v.decoderRegistry = r
 	})
 }
@@ -72,6 +80,10 @@ func WithDecoderRegistry(r DecoderRegistry) Option {
 // WithCodecRegistry sets a custom [EncoderRegistry] and [DecoderRegistry].
 func WithCodecRegistry(r CodecRegistry) Option {
 	return optionFunc(func(v *Viper) {
+		if r == nil {
+			return
+		}
+
 		v.encoderRegistry = r
 		v.decoderRegistry = r
 	})

finder.go

@@ -9,6 +9,10 @@ import (
 // WithFinder sets a custom [Finder].
 func WithFinder(f Finder) Option {
 	return optionFunc(func(v *Viper) {
+		if f == nil {
+			return
+		}
+
 		v.finder = f
 	})
 }
@@ -34,6 +38,10 @@ func (c *combinedFinder) Find(fsys afero.Fs) ([]string, error) {
 	var errs []error
 
 	for _, finder := range c.finders {
+		if finder == nil {
+			continue
+		}
+
 		r, err := finder.Find(fsys)
 		if err != nil {
 			errs = append(errs, err)

viper.go

@@ -247,6 +247,10 @@ type StringReplacer interface {
 // EnvKeyReplacer sets a replacer used for mapping environment variables to internal keys.
 func EnvKeyReplacer(r StringReplacer) Option {
 	return optionFunc(func(v *Viper) {
+		if r == nil {
+			return
+		}
+
 		v.envKeyReplacer = r
 	})
 }