Update CLAUDE.md and README: fix stale filename, document error atoms

Author: lpgauth

CLAUDE.md

@@ -8,7 +8,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 TORQUE_BUILD=true mix deps.get     # fetch deps + force local Rust build
 TORQUE_BUILD=true mix compile      # build (includes Rust NIF compilation)
 TORQUE_BUILD=true mix test         # run all tests
-mix test test/torque_test.exs:42   # run single test by line number
+mix test test/pointer_test.exs:42  # run single test by line number
 mix compile --warnings-as-errors   # build with strict warnings
 mix format                         # format Elixir code
 mix format --check-formatted       # check Elixir formatting
@@ -67,4 +67,4 @@ Inputs larger than 10 KB are automatically dispatched to dirty CPU schedulers to
 - `native/torque_nif/src/decoder.rs` — parse, get, get_many, decode NIFs
 - `native/torque_nif/src/encoder.rs` — direct term-walking JSON encoder
 - `native/torque_nif/src/types.rs` — sonic_rs Value → Erlang term conversion
-- `native/torque_nif/src/atoms.rs` — cached atoms (ok, error, no_such_field, nil)
+- `native/torque_nif/src/atoms.rs` — cached atoms (ok, error, nil, no_such_field, nesting_too_deep, unsupported_type, non_finite_float, invalid_key, malformed_proplist, invalid_utf8)

README.md

@@ -116,6 +116,29 @@ For objects with duplicate keys, the last value wins.
 | atom | string |
 | `{keyword_list}` | object |
 
+## Errors
+
+Functions return `{:error, reason}` tuples (or raise `ArgumentError` for bang/iodata variants). Possible `reason` atoms:
+
+### Decode / Parse
+
+| Atom | Returned by | Meaning |
+|------|-------------|---------|
+| `:nesting_too_deep` | `decode/1`, `parse/1`, `get/2,3` | Document exceeds 512 nesting levels |
+
+`parse/1` and `decode/1` also return `{:error, binary}` with a message from sonic-rs for malformed JSON.
+
+### Encode
+
+| Atom | Returned by | Meaning |
+|------|-------------|---------|
+| `:unsupported_type` | `encode/1` | Term has no JSON representation (PID, reference, port, …) |
+| `:invalid_utf8` | `encode/1` | Binary string or map key is not valid UTF-8 |
+| `:invalid_key` | `encode/1` | Map key is not an atom or binary (e.g. integer key) |
+| `:malformed_proplist` | `encode/1` | `{proplist}` contains a non-`{key, value}` element |
+| `:non_finite_float` | `encode/1` | Float is infinity or NaN (unreachable from normal BEAM code) |
+| `:nesting_too_deep` | `encode/1` | Term exceeds 512 nesting levels |
+
 ## Benchmarks
 
 Apple M2 Pro, OTP 28, Elixir 1.19: