diag: somewhere for swallowed errors to go

A TUI must not die because one background load failed, so this codebase catches
broadly -- ~50 `except Exception` sites, two dozen resolving to `pass`. Right
policy, one bad consequence: with 44 `@work(thread=True)` workers, a failure in
a background load leaves no trace whatsoever. The view stays empty and there is
nothing to read afterwards, because the app owns the screen.

kittygfx already solved this for itself with $IDATUI_KITTY_LOG. idatui/diag.py
is the same idea for everything else: $IDATUI_LOG writes every swallowed error
plus its traceback to a file, and the last 50 are kept in memory regardless so a
driver can ask a live app what went wrong. Unset, it costs an environ lookup.

Wired in where losing the error changes a DECISION rather than just a pixel:

  * rename: a resolve() that throws renames as DATA instead of as a function.
  * name: a function_of() that throws means we never learn the address is a
    function start, so the index keeps the old name and every readback says the
    rename didn't happen.
  * retype: a resolve() that throws retypes the ENCLOSING function instead.
  * decompile: a failed full-body fetch silently returns CLIPPED pseudocode.
  * trail: a failed decomp_map stops the pseudocode being painted, silently.

Deliberately NOT wired into the query_one guards -- a modal owning the screen is
normal and constant, and logging it would bury the real entries in noise.

New RPC verb `diag {n?, clear?}`, documented in docs/RPC.md: the answer to "the
verb reported success and the pane shows nothing".

Also a flake, same shape as the others: follow_xrefs waited on the nav depth but
asserted on _cur, and a follow pushes the source entry BEFORE opening the
target -- so the check could run in between and see the function it jumped
from. About one run in ten. It waits on the postcondition it asserts now; three
clean full runs since.

833 checks; --fast is 344 in 3.5s.

1 files changed, 11 insertions, 0 deletions

diff --git a/idatui/rpc.py b/idatui/rpc.py
index b4ca80e..698e4cf 100644
--- a/idatui/rpc.py
+++ b/idatui/rpc.py
@@ -28,6 +28,7 @@ from typing import Any
 from rich.console import Console
 
 from ._sync import drain, settle
+from . import diag
 from .app import DecompView, GraphView, HexView, ListingView, ViewMode
 
 PROTO_VERSION = 1
@@ -889,6 +890,16 @@ class RpcServer:
             return functions(app, params.get("filter"), int(params.get("limit", 50)))
 
         # -- projects ------------------------------------------------------ #
+        if method == "diag":
+            # What has been swallowed lately. A driver that got "success" and a
+            # pane showing nothing has no other way to ask; inside a
+            # full-screen TUI there is nowhere for a traceback to go.
+            if params.get("clear"):
+                diag.clear()
+                return {"cleared": True}
+            return {"recent": diag.recent(int(params.get("n", 10))),
+                    "log": os.environ.get("IDATUI_LOG") or None}
+
         if method == "trace":
             tc = app.trace_ctl
             if tc.trace is None: