Handle potentially null json

Author: code-asher

src/main/kotlin/com/coder/gateway/sdk/CoderCLIManager.kt

@@ -291,7 +291,7 @@ class CoderCLIManager @JvmOverloads constructor(
         return try {
             val raw = exec("version", "--output", "json")
             val json = Gson().fromJson(raw, Version::class.java)
-            json.version
+            json?.version
         } catch (e: Exception) {
             logger.warn("Unable to determine CLI version: ${e.message}")
             null