📝 update sax_parse documentation (#4878)

Author: nlohmann

docs/mkdocs/docs/api/basic_json/sax_parse.md

@@ -51,10 +51,10 @@ The SAX event lister must follow the interface of [`json_sax`](../json_sax/index
 ## Parameters
 
 `i` (in)
-:   Input to parse from.
+:   Input to parse from
 
 `sax` (in)
-:   SAX event listener
+:   SAX event listener (must not be null)
 
 `format` (in)
 :    the format to parse (JSON, CBOR, MessagePack, or UBJSON) (optional, `input_format_t::json` by default), see
@@ -83,6 +83,17 @@ return value of the last processed SAX event
 
 ## Exception safety
 
+Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
+
+## Exceptions
+
+- Throws [`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101) in case of an unexpected token, or
+  empty input like a null `FILE*` or `char*` pointer.
+- Throws [`parse_error.102`](../../home/exceptions.md#jsonexceptionparse_error102) if `to_unicode` fails or surrogate
+  error.
+- Throws [`parse_error.103`](../../home/exceptions.md#jsonexceptionparse_error103) if `to_unicode` fails.
+- Throws [`other_error.502`](../../home/exceptions.md#jsonexceptionother_error502) if `sax` is a null pointer.
+
 ## Complexity
 
 Linear in the length of the input. The parser is a predictive LL(1) parser. The complexity can be higher if the SAX
@@ -114,6 +125,7 @@ A UTF-8 byte order mark is silently ignored.
 - Added in version 3.2.0.
 - Ignoring comments via `ignore_comments` added in version 3.9.0.
 - Added `ignore_trailing_commas` in version 3.12.1.
+- Added `json.exception.other_error.502` exception in version 3.12.1.
 
 !!! warning "Deprecation"
 

docs/mkdocs/docs/home/exceptions.md

@@ -903,7 +903,7 @@ A JSON Patch operation 'test' failed. The unsuccessful operation is also printed
 
 ### json.exception.other_error.502
 
-This exception occurs when a null pointer is passed as SAX handler in [sax_parse](../api/basic_json/sax_parse.md) function.
+This exception is thrown when a null pointer is passed as SAX event listener to the [sax_parse](../api/basic_json/sax_parse.md) function.
 
 !!! failure "Example message"