Build wasm

Hi there thanks for this great project!

I am building the Make File to load a custom SQLite extension.
Unfortunately the build fails. I have not modified the make file yet.
I think its emcc that's failing.

emcc --memory-init-file 0 -s RESERVED_FUNCTION_POINTERS=64 -s ALLOW_TABLE_GROWTH=1 -s EXPORTED_FUNCTIONS=@src/exported_functions.json -s EXPORTED_RUNTIME_METHODS=@src/exported_runtime_methods.json -s SINGLE_FILE=0 -s NODEJS_CATCH_EXIT=0 -s NODEJS_CATCH_REJECTION=0 -Oz -flto --closure 1 -s WASM=0 out/sqlite3.bc out/extension-functions.bc --pre-js src/api.js -o dist/sql-asm.js
building:ERROR: Closure compiler run failed:

building:ERROR: /tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:239:30: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. expected closing } See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  239|     @return {Database.SqlValue[]} One row of result
                                     ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:282:19: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. expected closing } See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  282|     @return {string[]} The names of the columns
                          ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:438:29: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. expected closing } See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  438|     @param {Database.SqlValue[]} values
                                    ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:438:29: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. expecting a variable name in a @param tag. See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  438|     @param {Database.SqlValue[]} values
                                    ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:588:20: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. expected closing } See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  588|     * @param {number[]} data An array of bytes representing
                           ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:588:20: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. expecting a variable name in a @param tag. See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  588|     * @param {number[]} data An array of bytes representing
                           ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:685:39: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. expected closing } See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  685|     * @return {Database.QueryExecResult[]} The results of each statement
                                              ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:736:42: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. missing closing ] See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  736|     @param {Statement.BindParams} [params=[]] Parameters to bind to the query
                                                 ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:927:22: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. missing opening ( See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  927|       @param {function} func the actual function to be executed.
                             ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:963:56: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. missing closing ] See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  963|       @param {function(): T} [aggregateFunctions.init = ()=>null]
                                                               ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:971:63: WARNING - [JSC_TYPE_PARSE_ERROR] Bad type annotation. missing closing ] See https://github.com/google/closure-compiler/wiki/Annotating-JavaScript-for-the-Closure-Compiler for more information.
  971|       @param {function(T): any} [aggregateFunctions.finalize = (state)=>state]
                                                                      ^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:359:15: ERROR - [JSC_UNDEFINED_VARIABLE] variable allocate is undeclared
  359|   var strptr = allocate(bytes, ALLOC_NORMAL);
                      ^^^^^^^^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:359:31: ERROR - [JSC_UNDEFINED_VARIABLE] variable ALLOC_NORMAL is undeclared
  359|   var strptr = allocate(bytes, ALLOC_NORMAL);
                                      ^^^^^^^^^^^^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:693:20: ERROR - [JSC_UNDEFINED_VARIABLE] variable allocateUTF8OnStack is undeclared
  693|    var nextSqlPtr = allocateUTF8OnStack(sql);
                           ^^^^^^^^^^^^^^^^^^^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:812:40: ERROR - [JSC_UNDEFINED_VARIABLE] variable removeFunction is undeclared
  812|   Object.values(this.functions).forEach(removeFunction);
                                               ^^^^^^^^^^^^^^

/tmp/emscripten_temp_1_4iazly/sql-asm.jso4.js:945:17: ERROR - [JSC_UNDEFINED_VARIABLE] variable addFunction is undeclared
  945|   var func_ptr = addFunction(wrapped_func, "viii");
                        ^^^^^^^^^^^

5 error(s), 11 warning(s)

I'm building this version of sqlite https://www.sqlite.org/2022/sqlite-amalgamation-3390300.zip
on WSL and installed the latest version of emcc

Any clues on what's going wrong?

Start by reproducing the make command shown in the issue with the reported SQLite amalgamation and emcc version. Inspect src/api.js, src/exported_functions.json, and src/exported_runtime_methods.json alongside the Closure Compiler errors; done means the build completes successfully with the custom extension.