Splitting results in Dynamic require of "<filename>" is not supported when targeting chrome62

[jluxenberg]

Description

We're trying out "splitting: true" using the ESM output format.

Our build currently targets chrome62.

When we enable splitting, I get the following error when the dynamic import is attempted:

Dynamic require of "<filename>" is not supported

Steps to reproduce

Try changing "chrome62" to "chrome63" here:
https://esbuild.github.io/try/#YgAwLjIwLjIALS1idW5kbGUgLS1vdXRkaXI9ZGlzdC8gLS1zcGxpdHRpbmcgLS1mb3JtYXQ9ZXNtIC0tdGFyZ2V0PWNocm9tZTYyAGUAZW50cnkuanMAY29uc3QgZjEgPSAoKSA9PiB7CiAgY29uc3QgeCA9IGltcG9ydCgnLi9maWxlLmpzJyk7CiAgY29uc29sZS5sb2coIngiLCB4KTsKfQoKZjEoKTsAAGZpbGUuanMAZXhwb3J0IGRlZmF1bHQgNDI7

Notice that in the "chrome62" version, the dynamic require is done via __require from the esbuild runtime.

You can try running the "chrome62" version in a browser, you will see the Dynamic require ... error.

Expected result

Dynamic imports work when targeting chrome62, or a build-time error is generated (e.g. "dynamic imports / splitting not supported on this target")

Actual result

The code is split into multiple chunks, however the code produced cannot actually dynamically import those chunks.