Getting the error when I iterate my data variable in for:each.Below is the snip of the values that is fetched in the data variable.Please help!

HTML

<table class="slds-table slds-table_cell-buffer slds-table_bordered">
                        <template for:each={data} for:item="con">
                            <tr key={con.key}>
                                <th style="height: 25px;">
                                    <div>{con}</div>
                                </th>
                            </tr>
                        </template>
                    </table>

JS

@track data;
getMergeLeads({Indexing:selectedIdsArray})
            .then(result => {
                var selectedIdRecords = result;
                this.data = selectedIdRecords;
                console.log('Get Merge Leads : '+JSON.stringify(this.data));
                
            })
            .catch(error => {
                this.error = error;
                console.log('Get Merge Leads error ===> '+error.body.message);
            });