Fail fast on empty wasmvm cache metric setup (backport #1576) (#1580)

* Fail fast on wasmvm cache metric setup

(cherry picked from commit 4595e6d)

* Adjust to the branch

---------

Co-authored-by: Alex Peters <alpe@users.noreply.github.com>

x/wasm/keeper/metrics.go

@@ -29,6 +29,9 @@ type WasmVMMetricsCollector struct {
 
 // NewWasmVMMetricsCollector constructor
 func NewWasmVMMetricsCollector(s metricSource) *WasmVMMetricsCollector {
+	if s == nil {
+		panic("wasmvm instance must not be nil")
+	}
 	return &WasmVMMetricsCollector{
 		source:             s,
 		CacheHitsDescr:     prometheus.NewDesc("wasmvm_cache_hits_total", "Total number of cache hits", []string{"type"}, nil),

x/wasm/keeper/options_test.go

@@ -1,6 +1,7 @@
 package keeper
 
 import (
+	"github.com/prometheus/client_golang/prometheus"
 	"reflect"
 	"testing"
 
@@ -31,6 +32,14 @@ func TestConstructorOptions(t *testing.T) {
 				assert.IsType(t, &wasmtesting.MockWasmer{}, k.wasmVM)
 			},
 		},
+		"vm cache metrics": {
+			srcOpt: WithVMCacheMetrics(prometheus.DefaultRegisterer),
+			verify: func(t *testing.T, k Keeper) {
+				t.Helper()
+				registered := prometheus.DefaultRegisterer.Unregister(NewWasmVMMetricsCollector(k.wasmVM))
+				assert.True(t, registered)
+			},
+		},
 		"decorate wasmvm": {
 			srcOpt: WithWasmEngineDecorator(func(old types.WasmerEngine) types.WasmerEngine {
 				require.IsType(t, &wasmvm.VM{}, old)