Implement BREAK and CONTINUE statements for WHILE loops

[Copilot]

Adds control flow statements BREAK and CONTINUE to exit or skip iterations in WHILE loops, following SQL-99/T-SQL syntax.

Changes

• Control flow via exceptions: Introduced BreakException and ContinueException that propagate through statement blocks to the enclosing loop
• WHILE loop: Added try-catch in While.prototype.execute to handle control flow exceptions
• BREAK/CONTINUE: Modified to throw exceptions instead of returning static values
• BeginEnd fix: Implemented synchronous execution path (was previously non-functional), allowing control flow exceptions to propagate naturally

Example

SET @a = 0;
SET @result = 0;
WHILE @a < 10
BEGIN
    SET @a = @a + 1;
    IF @a = 8 BREAK;           -- Exits loop when @a reaches 8
    IF @a % 2 = 0 CONTINUE;    -- Skips even numbers
    SET @result = @result + @a;
END;
-- @result = 16 (sum of 1,3,5,7)

Exceptions propagate through nested BEGIN...END blocks correctly. Test suite (test/test37.js) covers simple loops, nested blocks, and edge cases.

Warning

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add BREAK and CONTINUE statements with more reliable WHILE statement</issue_title>
<issue_description>Add statements like:

    SET @a = 1;
    WHILE @a < 10
    BEGIN
        IF @a = 8 BREAK;
        SET @a += 1;
        IF @a = 5 CONTINUE;
        SET @a += 1;
     END;

</issue_description>

<agent_instructions>start by making a testfile named test37.js, describe the needed behavour based on SQL-99

Then try to solve it. </agent_instructions>

Comments on the Issue (you are @copilot in this section)

@mathiasrw Has this been resolved?

• Fixes Add BREAK and CONTINUE statements with more reliable WHILE statement #37

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