Refuse a malformed DATABASE_URL without printing the password

CHANGELOG.md

@@ -8,6 +8,14 @@ Newest first. `Unreleased` is what is on `main` and not yet tagged.
 
 ## Unreleased
 
+### A malformed `DATABASE_URL` is refused without printing the password
+
+`DATABASE_URL` is taken apart before it reaches Bun, and the string most likely to fail that parse is
+one with a stray character in the password. The refusal for an unparseable value quoted the whole
+string back to name the fault, which wrote the database password into the log line that reported it.
+It now names the variable and the shape it expects, the way the other refusals beside it already do,
+and never echoes the value.
+
 ### Wiping a computer is recorded even if clearing its stored state fails
 
 Resetting a computer destroys the profile first and wrote the audit row last, after two Postgres

server/src/db/client.ts

@@ -40,8 +40,12 @@ function addressOf(databaseUrl: string) {
   try {
     url = new URL(databaseUrl);
   } catch {
+    // The value is not echoed back. DATABASE_URL holds the database password, and the one string
+    // most likely to fail `new URL` is one with a stray character in that password, so printing it
+    // to name the fault would put the credential in the log line that reports it. Name the variable
+    // and the shape it expects, the way every other refusal in this function does.
     throw new TypeError(
-      `DATABASE_URL is not a URL: ${JSON.stringify(databaseUrl)}`,
+      "DATABASE_URL is not a valid URL. Expected postgres://user:password@host:port/database.",
     );
   }
   if (url.hostname === "") {

server/tests/db-client-address.test.ts

@@ -27,12 +27,28 @@ describe("the database address", () => {
     expect(process.env.DATABASE_URL).toBeUndefined();
   });
 
-  test("refuses a connection string that is not a URL, naming what it got", () => {
+  test("refuses a connection string that is not a URL", () => {
     expect(() => createDatabase("://openbot@/openbot")).toThrow(
-      /DATABASE_URL is not a URL/,
+      /DATABASE_URL is not a valid URL/,
     );
   });
 
+  test("does not put the password in the message when the URL will not parse", () => {
+    // A stray character in a generated password is the likeliest reason `new URL` throws here, so
+    // the refusal must not echo the string it was given: DATABASE_URL carries the credential, and a
+    // message quoting it would write the password into the log line that reports the fault. The
+    // invalid port makes `new URL` throw with the secret still present in the input.
+    const secret = "s3cr3t-p4ssw0rd";
+    let message = "";
+    try {
+      createDatabase(`postgres://openbot:${secret}@127.0.0.1:notaport/openbot`);
+    } catch (error) {
+      message = error instanceof Error ? error.message : String(error);
+    }
+    expect(message).toMatch(/DATABASE_URL is not a valid URL/);
+    expect(message).not.toContain(secret);
+  });
+
   test("refuses a URL with no host, which would otherwise parse and connect nowhere", () => {
     // `new URL` accepts this: the scheme is "openbot:" and there is no host at all.
     expect(() => createDatabase("openbot:openbot@localhost/openbot")).toThrow(