Properly handle conditions when finding server trace
@@ -77,7 +77,7 @@ module Selenium
server_trace = error_payload[STACKTRACE_KEY] ||
error_payload[STACKTRACE_KEY.downcase] ||
- error_payload['value'] && error_payload['value'][STACKTRACE_KEY]
+ (error_payload['value'] && error_payload['value'][STACKTRACE_KEY])
return unless server_trace
backtrace = case server_trace
