fix(core): fix empty runtimeContext check

Before this fix, calls to service action handlers for services with
runtime dependencies in template variables would fail if an empty
runtimeContext was passed, even if the service handler in question
doesn't need environment variables (e.g. getServiceStatus and
getServiceLogs).

garden-service/src/actions.ts

@@ -772,7 +772,11 @@ export class ActionRouter implements TypeGuard {
     })
 
     // Resolve ${runtime.*} template strings if needed.
-    if (runtimeContext && (await getRuntimeTemplateReferences(module)).length > 0) {
+    const runtimeContextIsEmpty = runtimeContext
+      ? Object.keys(runtimeContext.envVars).length === 0 && runtimeContext.dependencies.length === 0
+      : true
+
+    if (!runtimeContextIsEmpty && (await getRuntimeTemplateReferences(module)).length > 0) {
       log.silly(`Resolving runtime template strings for service '${service.name}'`)
       const configContext = await this.garden.getModuleConfigContext(runtimeContext)
       const graph = await this.garden.getConfigGraph(log, { configContext })