Type generation tool is not correctly handling nullable fields in TypeScript

I'm building a code generation tool that takes in an input file of my database schema as an interface and generates smaller types from that.

Input

export interface Database {
public: {
Tables: {
profiles: {
Row: {
first_name: string | null;
id: string;
last_name: string | null;
};
};
};
};
}

Expected Output

export type Profile = {
first_name: string | null;
id: string;
last_name: string | null;
};

Actual Output

export type Profile = {
first_name: string;
id: string;
last_name: string;
};

I'm having trouble capturing the null parts of my output when generating my types.

What I've currently got

const project = new Project({
compilerOptions: {
allowSyntheticDefaultImports: true,
esModuleInterop: true,
module: ModuleKind.ESNext,
target: ScriptTarget.ESNext,
},
});
const sourceFile = project.addSourceFileAtPath(typesPath);
// Find the 'Tables' type alias
const databaseInterface = sourceFile.getInterfaceOrThrow('Database');
const publicProperty = databaseInterface.getPropertyOrThrow('public');
const publicType = publicProperty.getType();
const tablesProperty = publicType
.getApparentProperties()
.find((property) => property.getName() === 'Tables');
const tablesType = project
.getProgram()
.getTypeChecker()
.getTypeAtLocation(tablesProperty.getValueDeclarationOrThrow());
const tablesProperties = tablesType.getProperties();
const types: string[] = [];
for (const table of tablesProperties) {
const tableName = table.getName();
types.push(...generateTypes(table, tableName));
}
...
export function generateTypes(table: Symbol, tableName: string): string[] {
// Get the table type
const tableType = table.getTypeAtLocation(table.getValueDeclarationOrThrow());
// Find the 'Row' property within the table type
const rowProperty = tableType.getProperty('Row');
// Get the type of the 'Row' property
const rowType = rowProperty.getTypeAtLocation(
rowProperty.getValueDeclarationOrThrow()
);
const rowTypeString = rowType.getText();
const types: string[] = [];
types.push(
`export type ${toTypeName(tableName)} = ${rowTypeString};`,
...
);
return types;
}

I've tried a lot of variations regarding what I've posted above but every single time I run my generate function I can't get it to print | null for those scenarios where properties could be null.

Using ts-morph v18.

Turn on the strictNullChecks compiler option:

const project = new Project({
  compilerOptions: {
    allowSyntheticDefaultImports: true,
    esModuleInterop: true,
    module: ModuleKind.ESNext,
    target: ScriptTarget.ESNext,
    strictNullChecks: true, // <-- this
  },
});

Otherwise the type checker ignores undefined/null in union types and thinks all types are not nullable (ts-morph uses the same defaults found in the typescript compiler).