Fix #266 where treeToValue extensions should be allowed to return nullable.

Author: apatrida

src/main/kotlin/com/fasterxml/jackson/module/kotlin/Extensions.kt

@@ -27,12 +27,12 @@ inline fun <reified T> ObjectMapper.readValue(src: Reader): T = readValue(src, j
 inline fun <reified T> ObjectMapper.readValue(src: InputStream): T = readValue(src, jacksonTypeRef<T>())
 inline fun <reified T> ObjectMapper.readValue(src: ByteArray): T = readValue(src, jacksonTypeRef<T>())
 
-inline fun <reified T> ObjectMapper.treeToValue(n: TreeNode): T = treeToValue(n, T::class.java)
+inline fun <reified T> ObjectMapper.treeToValue(n: TreeNode): T? = treeToValue(n, T::class.java)
 inline fun <reified T> ObjectMapper.convertValue(from: Any): T = convertValue(from, jacksonTypeRef<T>())
 
 inline fun <reified T> ObjectReader.readValueTyped(jp: JsonParser): T = readValue(jp, jacksonTypeRef<T>())
 inline fun <reified T> ObjectReader.readValuesTyped(jp: JsonParser): Iterator<T> = readValues(jp, jacksonTypeRef<T>())
-inline fun <reified T> ObjectReader.treeToValue(n: TreeNode): T = treeToValue(n, T::class.java)
+inline fun <reified T> ObjectReader.treeToValue(n: TreeNode): T? = treeToValue(n, T::class.java)
 
 internal fun JsonMappingException.wrapWithPath(refFrom: Any?, refFieldName: String) = JsonMappingException.wrapWithPath(this, refFrom, refFieldName)
 internal fun JsonMappingException.wrapWithPath(refFrom: Any?, index: Int) = JsonMappingException.wrapWithPath(this, refFrom, index)