[metrics] Fixes custom metrics type checking

Author: jacomyal

packages/gephi-lite/src/core/metrics/edges/edgeScript.ts

@@ -1,5 +1,4 @@
-import { isBoolean, isNumber, isString } from "lodash";
-
+import { isScalar } from "../../../utils/check";
 import { graphDatasetAtom } from "../../graph";
 import { FullGraph } from "../../graph/types";
 import { dataGraphToFullGraph } from "../../graph/utils";
@@ -36,8 +35,8 @@ export const edgeScript: Metric<{ edges: ["custom"] }> = {
         const id = fullGraph.edges()[0];
         const attributes = fullGraph.getEdgeAttributes(id);
         const result = fn(id, attributes, 0, fullGraph);
-        if (!isNumber(result) && !isString(result) && !isBoolean(result))
-          throw new Error("Function must returns a number or a string");
+        if (!isScalar(result))
+          throw new Error("Function must returns a number, a string, a boolean, null or undefined");
       },
       defaultValue: edgeMetricCustomFn,
     },

packages/gephi-lite/src/core/metrics/nodes/nodeScript.ts

@@ -1,5 +1,4 @@
-import { isBoolean, isNumber, isString } from "lodash";
-
+import { isScalar } from "../../../utils/check";
 import { graphDatasetAtom } from "../../graph";
 import { FullGraph } from "../../graph/types";
 import { dataGraphToFullGraph } from "../../graph/utils";
@@ -36,8 +35,8 @@ export const nodeScript: Metric<{ nodes: ["custom"] }> = {
         const id = fullGraph.nodes()[0];
         const attributs = fullGraph.getNodeAttributes(id);
         const result = fn(id, attributs, 0, fullGraph);
-        if (!isNumber(result) && !isString(result) && !isBoolean(result))
-          throw new Error("Function must return either a number or a string");
+        if (!isScalar(result))
+          throw new Error("Function must returns a number, a string, a boolean, null or undefined");
       },
       defaultValue: nodeMetricCustomFn,
     },

packages/gephi-lite/src/utils/check.ts

@@ -1,4 +1,15 @@
+import { Scalar } from "@gephi/gephi-lite-sdk";
 import checkIsUrl from "is-url";
+import { isNil } from "lodash";
+
+const NON_NIL_SCALAR_TYPES = new Set(["boolean", "number", "string"]);
+
+/**
+ * Check if a value is a scalar value.
+ */
+export function isScalar(value: unknown): value is Scalar {
+  return isNil(value) || NON_NIL_SCALAR_TYPES.has(typeof value);
+}
 
 /**
  * Check if a string is a valid url.