[Bug]: on fail does not support having multiple error types

[suleka96]

Description

As of now, union support for on fail clause is not available, thus having multiple errors is not supported. The same issue is present in foreach as both traverse through the same resolving path.

Steps to Reproduce

type SampleErrorData record {|
    int code;
    string reason;
|};

type SampleError error<SampleErrorData>;

type SampleComplexErrorData record {|
    error cause;   
    int code;
    int[2] pos;
    record {string moreInfo;} infoDetails;
|};

type SampleComplexError error<SampleComplexErrorData>;

public function main() {
    boolean isPositiveState = false;
      do {
        if isPositiveState {
            fail error SampleComplexError("Transaction Failure", cause = error("Database Error"), code = 20,  pos = [30, 45], infoDetails = {moreInfo: "deadlock condition"}); 
        }
        fail error SampleError("Transaction Failure", code = 50, reason = "deadlock condition");
    } on fail var error(_, pos = [tr, ty]) {
            io:println(tr);
    }
}

This gives the below errors:

ERROR [test7.bal:(80:34,80:42)] invalid list binding pattern: expected an array or a tuple, but found 'ballerina/lang.value:0.0.0:Cloneable'
ERROR [test7.bal:(81:24,81:26)] undefined symbol 'tr'

Affected Version(s)

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OS, DB, other environment details and versions

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Related area

-> Compilation

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