harden: debug mode logs only a request's origin and JSON-RPC method (closes #410)

With debug mode on, debugFetch logged every request's full URL and body,
so an RPC endpoint with an API key in its path or query string printed
that key to the console on every request. It now logs the HTTP method,
the URL's origin and, for a JSON-RPC body, the method name. The balance
refresh and token lookup log the RPC endpoint by its origin too. Failed
RPC calls print ethers' short message, since its full message for an
HTTP error carries the request URL. A failed endpoint check in settings
prints the endpoint's origin, since fetch's error for a URL with a user
name and password carries the whole URL. The README's DEBUG Mode Policy
says what debug mode logs.

Model: opus-5-5

src/popup/views/settings.js

@@ -16,7 +16,12 @@ const {
 } = require("../dustThreshold");
 const { state, saveState, currentNetwork } = require("../../shared/state");
 const { onChainSwitch } = require("../../shared/chainSwitch");
-const { log, debugFetch, setRuntimeDebug } = require("../../shared/log");
+const {
+    log,
+    debugFetch,
+    urlOrigin,
+    setRuntimeDebug,
+} = require("../../shared/log");
 const deleteWallet = require("./deleteWallet");
 const showPhrase = require("./showPhrase");
 const { walletHasRecoveryPhrase } = require("../../shared/wallet");
@@ -272,8 +277,11 @@ function init(ctx) {
                 showFlash("Wrong network: expected " + net.name + ".");
                 return;
             }
-        } catch (e) {
-            log.errorf("RPC validation fetch failed:", e.message);
+        } catch {
+            // Not the error's message: fetch puts the whole URL, password and
+            // key included, in the message of the error it throws for a URL
+            // with a user name and password or one it cannot parse.
+            log.errorf("RPC validation fetch failed:", urlOrigin(url));
             showFlash("Could not reach endpoint.");
             return;
         }
@@ -295,8 +303,9 @@ function init(ctx) {
                 showFlash("Endpoint returned HTTP " + resp.status + ".");
                 return;
             }
-        } catch (e) {
-            log.errorf("Blockscout validation failed:", e.message);
+        } catch {
+            // Not the error's message, as for the RPC check above.
+            log.errorf("Blockscout validation failed:", urlOrigin(url));
             showFlash("Could not reach endpoint.");
             return;
         }