Schema generator does not add new indexes when updating

[bahdcoder]

Describe the bug

When running schemaGenerator.updateSchema(), new unique indexes added to the column do not get created.

To Reproduce
Steps to reproduce the behavior:

1. Create an entity such as Article with a slug string column.
2. Create the articles table and slug field in the database.
3. Run schema generator update schema method. Notice the new index is not created.

Expected behavior
A clear and concise description of what you expected to happen.

Additional context

1. I have only tested this on mysql.
2. I believe this is the origin of the problem after spending a moment debugging:

// @mikro-orm/knex/SchemaHelper

    hasSameIndex(prop, column) {
        if ([core_1.ReferenceType.SCALAR, core_1.ReferenceType.EMBEDDED].includes(prop.reference)) {
            // TODO: Check indexes on scalar fields instead of returning true.
            return true;
        }
        return prop.referencedColumnNames.some(referencedColumnName => {
            return !!column.fk && referencedColumnName === column.fk.referencedColumnName && prop.referencedTableName === column.fk.referencedTableName;
        });
    }

Versions

Dependency	Version
node	12.17.0
typescript	3.9.5
mikro-orm	4.2.0
your-driver	mysql

[B4nan]

Index diffing happens in findIndexDifference method (hasSameIndex is used only for diffing FK indexes), but that was adding missing indexes only for those defined on entity level (those are stored in meta.indexes and meta.uniques), not on property level (stored on meta.properties[prop].index and unique respectively).